L.U.
okay, L.- my father works on the board for L(ake)W(ashington)Y(outh)S(occer)A(ssociation) or LWYSA for short. Your sister needs to talk to the father and tell him that she is the coach and he needs to back off. If he can't then he and his daughter will be off the team. It's unfair to his daughter, I know, but it's unfair to the other 10ish kids that are playing on the team to hear a man berate and control them. Your sister needs to remember that it is affecting her a lot, and it's hurting her....think how those other kids must be feeling.
Also, I know that if they are playing a game and the father is going crazy and yelling stuff from the sidelines (which is "illegal" in soccer games, not even the coach is supposed to yell, but especially not the parents) the reff can actually card him and ask him to leave the field. But, what usually happens, the reff speaks to the coach first and tells him/her to control her parents.
you would be surprised with the stories I have heard about parents that are out of control, yelling horrible things at children and reffs, throwing things, and just being very immature. Your sister needs to make that man stop NOW, or get him and his daughter off the team. She can talk to the soccer board about how to do that. Good luck to her!
L.